code: def __count_actual_buf(info, buf_var_lives):
      # count how many buffers are required at maximum based on buf_var_lives
      actual_buf_num = 0
      for func_idx, _ in enumerate(info._network.function):
          buf_num = 0
          for buf_idx, buf_var_life in enumerate(buf_var_lives):
              buf_num += int(buf_var_life.needed_at(func_idx))
          actual_buf_num = max(actual_buf_num, buf_num)
      return actual_buf_num
  
file_path: nnabla/python/src/nnabla/utils/converter/nnablart/save_variable_buffer.py
imports: import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: __count_actual_buf(info, buf_var_lives) and returns: actual_buf_num